Typically, instrument panel (IP) cockpit systems consists of a cross-vehicle structural member or beam, generally constructed out of a steel or cast magnesium tube, which carries the load from a steering column extending between a steering mechanism, for example, a steering wheel, and a torque distribution mechanism. The steering column is designed to translate rotation of the steering wheel by a vehicle operator to the torque distribution mechanism, which correspondingly positions the wheels of the vehicle in accordance with the position of the steering wheel, thus steering the vehicle. An issue in most steel beam systems is their high overall mass along with other issues discussed below namely, bracket inaccuracy after welding to the steel beam, beam distortion after welding of brackets to the beam, fit of HVAC module around beam and/or vice versa, minimizing clearances between HVAC ductwork and beam. Other problems include inconsistencies or inefficiencies of the packaging of the beam, HVAC and associated ductwork to maximize available vehicle interior cabin space as well as numerous fasteners and fastening steps, which increase manufacturing costs. In addition, the large amount of component parts and low integration levels create high material costs.
Issues present in magnesium beam systems, are tooling life, high cost of magnesium material, lack dimensional consistency mold-to-mold, high quantity of assembly operations, and limited integration opportunity.
The cross-vehicle structural member is generally a load-bearing member that is used to support attachments such as the instrument panel trim cover and other trim components, airbag module, center console stack, instrument cluster, heating ventilation and air conditioning (HVAC) module, air ducting components, etc. The components of the HVAC module, for example, are attached about the cross-vehicle structural member, such that some components are located on the upper portion of the structural member and other components are located on the lower portion of the structural member, or located about both portions of the structural member depending on the vehicle. The manner in packaging the HVAC and ductwork around the structural member and to the vehicle can minimize the available vehicle interior cabin space. Furthermore, attaching the HVAC module to the structural member allows for undesirable clearances between the HVAC ductwork and the structural member. In another example, the airbag module is generally attached to the structural member either in the upper portion or lower portion of the structural member or both. The airbag module includes an airbag inflator bracket provided to attach the airbag components to the structural member using, for example, one or more threaded bolts and corresponding nuts which can raise both assembly costs and material costs.
Other components, such as, for example, energy absorbing brackets used to manage knee intrusions to the instrument panel upon collision are also attached to a portion of the structural member via arc welding or the use of one or more mechanical fasteners. Additional vehicle components welded or mechanically attached to the beam include center support brackets, instrument panel support brackets, cluster support brackets, HVAC mount brackets and glove box attachment brackets. Moreover, these brackets are typically secured using welding techniques (e.g., arc welding) that result inaccuracies in bracket location due to material distortion by for example, the high temperatures associated with the arc welding process. As such, issues that are present with these current structural beam assemblies include, but are not limited to, having large number of individual components and low integration potential (e.g. high material costs). In addition, the dimensional compliance of the beam assembly will be less due to the amount of components being secured thereto and the methods used for securement (e.g., arc welding).
Accordingly, it is desirable to have an integrated structural system that integrally molds an upper beam component that defines a housing for receiving an airbag module to a structural member for reducing system cost by eliminating a separate inflator/airbag housing as well as improve upon the registration of the airbag assembly to the instrument panel. It is also desirable to have an integrated structural system that integrally welds a lower beam component that defines an HVAC module and other components (e.g. air ducting module) to the upper beam component or structural member for providing the use of common surfaces between components, eliminating separate components, eliminating clearances between components, and minimizing system noise, vibrations, and harshness (NVH) issues as well as mass.
Additionally desirable is an integrated structural system that includes a structural member that can be manufactured from a single material but can also be comprised of multiple sections of different material types and/or wall thicknesses welded together using an improved welding technique to form a structural member possessing a high level of stiffness and energy management properties as well as meet vehicle requirements while minimizing cost and mass of the construction. Likewise, the use of technology such as deformation resistance welding to join the steel tubes facilitates the production of a strong, dimensionally accurate weld using similar or dissimilar materials is also desirable. It is also desirable to use such technology to weld end brackets on each end of the structural member for securing the structural member to the shear walls of the vehicle.
Furthermore, it is desirable to have an integrated structural system that uses an improved molding technique that eliminates the potential for metal tube crush during molding, facilitates improved surface finish, enables use of plastic composite materials on complex part designs without compromising dimensional accuracy, provides for little or no increase in molding process cycle time, enables for the production of a lightweight over molded metal reinforced structure, and provides for the ability to further minimize and vary the part wall thickness. It is also desirable to have an integrated structural system that greatly enhances the ability to tailor the beam material type, wall thickness, and section shape to precisely meet vehicle requirement.